The art is rich in proposals for backpack flames adapted to dual uses such as supporting a backpack and also serving as a stool, chair, stretcher, or bed. While the major focus of the art has been the multiple use characteristic, there has been little advancement distinguished for the materials used in the frame's construction or in the simplicity of design which would aid the practical use of such a dual purpose pack frame.
Despite continuous development of multi-use frame designs, there is still no design contemplating a cot use that has enjoyed substantial success in the market place. One of the principle reasons for this lack of commercial acceptance is that previous inventions are designed around age old technology using tubular aluminum piping commensurate with recreational chairs and recliners with the consequent result of the frame manifesting a bulk and weight exceeding that for practical use in backpacking or military maneuvering. For example, U.S. Pat. No. 3,828,992 entitled FOLDING COT PACK by J. Cerchione, discloses in its main embodiment the use of tubular metal. Moreover, the design cannot be folded in a totally flat compact arrangement. Thus, the design inherently causes the center of balance of the tubular metal frame to rest considerably rearward to that of the wearer's center of gravity. Additionally, the design does not allow ready access to the pack contents while being worn on the hiker's back.
Although the prior art describes convertible pack frames that are essentially flat and designed such that the bulk of the frame's weight rests in close proximity to the wears back, such designs do not address practicability of use for several reasons. For instance, U.S. Pat. No. 4,947,498 entitled PORTABLE COLLAPSIBLE BED by L. Van Boxtel, describes a convertible frame that can be unfolded from a flat compact arrangement made of two sections. The main practical problem with such a design is that in order for the two sections, when in the unfolded position, to provide a length necessary for a man of average height to lay upon, each section would necessarily be about 36 inches in length. Thus, when wearing the frame on the back, taking into consideration the use of a supporting waist belt, the top of the pack and frame would extend substantially above the wears head causing the center of balance to be considerably raised and necessarily create a top heavy arrangement of the carried weight. Moreover, since a main object of the present invention is use for military infantry, a pack frame of such dimensions and arrangement is unacceptable.
In U.S. Pat. No. 4,538,750 entitled CONVERTIBLE BED AND PACK FRAME by K. Hanna, a compact frame is also described which is designed to rest close to the wearer's back. However, the described frame is a multi-component system and must be assembled from separate detachable parts each time the frame is converted to the cot configuration. Although the invention has relatively few separate components, the fact of separable components and the necessity of assembly is not optimal for use under rugged conditions. Concerning convertible pack frames that have multiple separable parts, U.S. Pat. No. 3,620,428 entitled CONVERTIBLE BACKPACK AND COT APPARATUS by J. Silverthone, is exemplary. The Silverthorne invention is a pack frame which is compact and designed to rest in close proximity of the wearer's center of gravity. However, the design is such that it has no less than nine separate parts of various shapes and sizes which must be dismantled during conversion between pack frame and cot configurations.
Still other designs, though requiring fewer parts nonetheless required reconfiguration of separable parts or are unstable as a sleeping platform. For example, in U.S. Pat. No. 2,973,888 entitled CONVERTIBLE CAMP COTS by H. Beardsley, some of the frame legs must be removed and repositioned while the length of the cot is expandable by use of a separate optional section. In U.S. Pat. No. 4,511,071 entitled COMBINATION BACKPACK FRAME AND COT by R. Curran, a frame is described in which both ends of the frame are slidably expandable frown a central section. Only the central section provides vertical support. Thus any weight, such as from the shifting of body weight, on the outer unsupported sections would cause the cot to topple to one side.
Consistent with tile above, there can be seen a need in tile art for new multipurpose pack frames, especially for frames convertible to a sleeping platform. Ideally, since the user of a backpack is normally in environments of unpredictable terrain and weather conditions, and is tested with extremes of physical demand, the multiple purpose of such pack frames should be understood to include frames having the capacity to effectively be put to practical use under rugged conditions, thus enabling the user to realize respite from his physical exertion in relative comfort. Such frames should specifically consider the materials to be used for construction as well as a design that allows the frame to be easily converted between uses without requiring separation of component parts.
Desirably, such a frame would facilitate the shaping and support of the pack material itself, be constructed of lightweight material, be compact not only in size of structural components but also in its folding arrangment, allow for minimum of effort in converting from folded to unfolded arrangement, allow for a center of gravity in close proximity to that of the wearer's spinal column, allow stability during use as a sleeping platform, avoid separable elements, and be cost effective to the extent that it would allow use both by recreational and military packers.
The present invention specifically addresses problems in the technology associated with backpack frames designed for multiple purposes. Typical, multipurpose designs have commonly used solid wood or hollow tubular aluminum alloy metal to form the frame's rigid structure. It is an object of the current invention to incorporate the use of carbon fiber and/or metalo-ceramic, hard plastic, and nylon materials instead of tubular aluminum and canvas. Regarding materials, a further object of the invention is to provide a method by which the structural components may be constructed. For instance, hard plastic or carbon fiber may be molded into component parts which can in turn be assembled to form the rigid side supports that support the sleeping platform material.
Additionally, the present invention addresses the issue of a need for multipurpose frames to avoid complex multi-component designs such as those in the prior art that required the user to carry out numerous and sometimes complex manipulations of frame components in order to convert the frame between uses. It is an object of the invention to provide a pack frame that does not require manipulation of separable components. The main embodiment of the current invention includes a design comprised of a foldable structure with three structural members, a head, middle, and leg section, which utilize a novel hinge arrangement allowing the structure to realize a near flat profile when in a folded configuration. Moreover, it is an additional object of the invention to provide a simple locking means in conjunction with the novel hinge arrangement to rigidify the overall structure while in either folded or unfolded configurations.
A preferred embodiment of the invention contemplates that when the frame is folded, the three structural members or sleeping platform sections are nearly completely flat in relation to one another. This aspect of the invention allows the wearer to maintain a center of gravity in close proximity to his natural gravitational center. Additionally, the folded frame allows for a minimum vertical length with respect to the length of the wearer's torso. The size of the overall dimensions of the frame's components can be adjusted according to the height and width of the wearer in that a frame can be built to accommodate people of various heights and shoulder widths. For instance, for a person six feet in height, the length of the head section is contemplated to be about two feet three inches while the middle and leg sections would be about two feet one inch and two feet two inches respectively. These measurements would give rise to a cot length approximately six feet two inches when the frame is unfolded forming the sleeping platform configuration. The overall loss of approximately four inches to the total length of the three sections taken together is due to overlap of the sections by about one inch of each section at the hinge assemblies located between the head and middle and the middle and leg sections.
Concerning military use, recent advancements in high technology warfare are making special demands on infantry of the day. Specifically, the use of infrared detection equipment has led to the desirability of reducing the infrared heat signal emanated by the individual soldier. It is well known that a living body lying in one location will transmit heat to the immediate environment and leave a strong heat or IR signal which can be detected long after the body heat source has vacated the area. Therefore it is an object of the invention for the use of an easily transportable sleeping cot to eliminate latent body heat markers from transferring to the surrounding soil and fauna which could expose the bedding location of infantry to IR detection equipped enemy aircraft. Thus, the vertical supports which support and raise the sleeping platform from the ground are intended to have a length from top to bottom of about 12 to 14 inches.
It is a further object of the invention to provide a sleeping platform made of a material with a reasonable degree of resiliency to provide a springy or cushion aspect to the sleeping platform and thereby enhance comfort. Materials contemplated can include nylon, rubber, and neoprene. Additionally, it is also contemplated that the frame be so constructed as to provide an easy and single means by which the bedding material can be removed and replaced.
Yet, another object of the invention is to provide a frame that actively engages the material of the pack itself to provide support and shape to the forward facing side, left and right sides, and bottom of the pack material.